const Eris = require('eris');
const transliterate = require('transliteration');
const moment = require('moment');
const uuid = require('uuid');
const humanizeDuration = require('humanize-duration');

const bot = require('../bot');
const knex = require('../knex');
const config = require('../config');
const utils = require('../utils');

const Thread = require('./Thread');
const {THREAD_STATUS} = require('./constants');

/**
 * @param {String} userId
 * @returns {Promise<Thread>}
 */
async function findOpenThreadByUserId(userId) {
  const thread = await knex('threads')
    .where('user_id', userId)
    .where('status', THREAD_STATUS.OPEN)
    .select();

  return (thread ? new Thread(thread) : null);
}

/**
 * Creates a new modmail thread for the specified user
 * @param {Eris.User} user
 * @returns {Promise<Thread>}
 * @throws {Error}
 */
async function createNewThreadForUser(user) {
  const existingThread = await findOpenThreadByUserId(user.id);
  if (existingThread) {
    throw new Error('Attempted to create a new thread for a user with an existing open thread!');
  }

  // Use the user's name+discrim for the thread channel's name
  // Channel names are particularly picky about what characters they allow, so we gotta do some clean-up
  let cleanName = transliterate.slugify(user.username);
  if (cleanName === '') cleanName = 'unknown';
  cleanName = cleanName.slice(0, 95); // Make sure the discrim fits

  const channelName = `${cleanName}-${user.discriminator}`;

  console.log(`[NOTE] Creating new thread channel ${channelName}`);

  // Attempt to create the inbox channel for this thread
  let createdChannel;
  try {
    createdChannel = await utils.getInboxGuild().createChannel(channelName);
    if (config.newThreadCategoryId) {
      // If a category id for new threads is specified, move the newly created channel there
      bot.editChannel(createdChannel.id, {parentID: config.newThreadCategoryId});
    }
  } catch (err) {
    console.error(`Error creating modmail channel for ${user.username}#${user.discriminator}!`);
    throw err;
  }

  // Save the new thread in the database
  const newThreadId = await createThreadInDB({
    status: THREAD_STATUS.OPEN,
    user_id: user.id,
    user_name: `${user.username}#${user.discriminator}`,
    channel_id: createdChannel.id,
    created_at: moment.utc().format('YYYY-MM-DD HH:mm:ss')
  });

  const newThread = await findById(newThreadId);

  // Post some info to the beginning of the new thread
  const mainGuild = utils.getMainGuild();
  const member = (mainGuild ? mainGuild.members.get(user.id) : null);
  if (! member) console.log(`[INFO] Member ${user.id} not found in main guild ${config.mainGuildId}`);

  let mainGuildNickname = null;
  if (member && member.nick) mainGuildNickname = member.nick;
  else if (member && member.user) mainGuildNickname = member.user.username;
  else if (member == null) mainGuildNickname = 'NOT ON SERVER';

  if (mainGuildNickname == null) mainGuildNickname = 'UNKNOWN';

  const userLogCount = await getClosedThreadCountByUserId(user.id);
  const accountAge = humanizeDuration(Date.now() - user.createdAt, {largest: 2});
  const infoHeader = `ACCOUNT AGE **${accountAge}**, ID **${user.id}**, NICKNAME **${mainGuildNickname}**, LOGS **${userLogCount}**\n-------------------------------`;

  await newThread.postSystemMessage(infoHeader);

  // Return the thread
  return newThread;
}

/**
 * Creates a new thread row in the database
 * @param {Object} data
 * @returns {Promise<String>} The ID of the created thread
 */
async function createThreadInDB(data) {
  const threadId = uuid.v4();
  const now = moment.utc().format('YYYY-MM-DD HH:mm:ss');
  const finalData = Object.assign({created_at: now, is_legacy: 0}, data, {id: threadId});

  await knex('threads').insert(finalData);

  return threadId;
}

/**
 * @param {String} id
 * @returns {Promise<Thread>}
 */
async function findById(id) {
  const row = await knex('threads')
    .where('id', id)
    .first();

  if (! row) return null;

  return new Thread(row);
}

/**
 * @param {String} channelId
 * @returns {Promise<Thread>}
 */
async function findByChannelId(channelId) {
  const thread = await knex('threads')
    .where('channel_id', channelId)
    .first();

  return (thread ? new Thread(thread) : null);
}

/**
 * @param {String} userId
 * @returns {Promise<Thread[]>}
 */
async function getClosedThreadsByUserId(userId) {
  const threads = await knex('threads')
    .where('status', THREAD_STATUS.CLOSED)
    .where('user_id', userId)
    .select();

  return threads.map(thread => new Thread(thread));
}

/**
 * @param {String} userId
 * @returns {Promise<number>}
 */
async function getClosedThreadCountByUserId(userId) {
  const row = await knex('threads')
    .where('status', THREAD_STATUS.CLOSED)
    .where('user_id', userId)
    .first(knex.raw('COUNT(id) AS thread_count'));

  return parseInt(row.thread_count, 10);
}

module.exports = {
  findOpenThreadByUserId,
  findByChannelId,
  createNewThreadForUser,
  getClosedThreadsByUserId,
};